<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>P155 7.2.3 【案例】改变盒子大小</title>
    <style>
        .box{width: 50px;height: 50px;background: #eee;margin: 0 auto;}
    </style>
</head>
<body>
    <div class="box" id="box"></div>
    <script>
        var box=document.getElementById('box');
        var i=0;
        box.onclick=function(){
            ++i;
            if(i%2){
                this.style.width='200px';
                this.style.height='200px';
                this.innerHTML='大';
            }else{
                this.style.width='50px';
                this.style.height='50px';
                this.innerHTML='小';
            }
        };
    </script>
</body>
</html>